The present invention generally relates to improvements in handling specimen slices cut by a microtome, and particularly relates to preventing curling of tissue slices cut by a cryogenic microtome.
For the purpose of making microscopic examinations of tissue samples, a tissue sample is typically placed in a microtome so that it can be sliced into thin specimens for staining and examination. Use of a cryogenic microtome and frozen tissue samples facilitates rapid examination in situations where an immediate diagnosis is necessary. Whether cryogenic or room temperature conditions prevail, it is imperative for proper diagnosis that a good cross-section of the sample be sliced and that the resultant slice be properly stored, that is prevented from curling or twisting or the like.
Heretofore, it has been known to provide a shield attached to the microtome. For example, in one known instance the shield is located proximate to the blade such that as the sample is sliced, the specimen slice is forced below the shield and along the top of the blade. It is then necessary to relocate the shield for access to the blade, and then transfer the specimen slices from the blade onto a slide for staining and diagnosis. The slices are lifted from the blade typically by placing a slide at room temperature quickly against the slices. The temperature differential causes the slices to adhere to the slide. It is extremely important that the specimen slices be prevented from rolling or curling or otherwise deforming in any manner which would prevent a flat, even cross-section from adhering to the slide for examination.
Although generally adequate for its intended purpose, such a known shield device forces the specimen slices to go along the microtome blade and away from the direction that they would naturally take due to the forces exerted by the blade during cutting. Furthermore, the presently known shield only directs the specimen slices toward the blade at the edge of the blade. Hence, as subsequent specimen slices engage the earlier slices (which have already adhered to or are resting on the blade) to force same to slide along the blade, the shield provides no mechanism for maintaining the specimen slices in a flat orientation so as to prevent them from curling, particularly when the shield is lifted.
Also, such a known shield requires frequent adjustment and considerable skill to obtain the necessary quality specimen slices. In addition, it is necessary to relocate the shield and remove the specimen slices from the microtome blade in some manner. In any event, static electricity may cause the slices to undesirably adhere to the shield rather than the blade, and thus may alter the slices causing them to be unusable. Because of these problems, many do not use this shield.
It has also been attempted to provide an anti-roll device to prevent curling of the slices. Such anti-roll device is a U-shaped member which extends down in front of the tissue sample and catches the specimen slice as it is cut, in a manner similar to a trapeze. Such a device requires considerable skill to operate and does not facilitate the transfer of the specimen slice onto a slide for microscopic examination. Further, it is difficult to keep the slices from falling off such device. Again, a typical result of such difficulties is that such device is not used in actual practice.
While various tissue slice handling problems can occur in virtually any type of microtome operations, the foregoing curling problems are particularly prevalent with frozen samples used during cryogenic operations. Room temperature tissue samples tend to have fewer curling problems since they are typically embedded with paraffin material.